Naltrexone Shows Promise as Fibromyalgia Treatment

A surprising medication – naltrexone – showed encouraging results for treating fibromyalgia pain and fatigue in a recent pilot study at the Stanford University School of Medicine. Why do I say it's a surprising medication? Because for more than 30 years, naltrexone has been used to treat opioid addiction.

At the dosages used to treat opioid addiction, naltrexone works by latching onto the body's opioid receptors and blocking their ability to induce a feeling of being high. It seems like this would block the body's pain-relief system. But given at lower dosages, it seems to have the opposite effect. The researchers think it may work by modulating glial cells in the nervous system, which provide support and protection for neurons and act as a link between the neuronal and inflammatory systems. Senior study author Sean Mackey, MD, PhD, associate professor of anesthesia and chief of the pain management division at Stanford University Medical Center, said, "We're learning more and more that maybe by modulating these glial cells we can impact the abnormal processing of pain in these patients."

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Normally I wouldn't report on a pilot study because there are so few participants – 10 in this case – that it's hard to put much stock in the results. However there are three reasons I think this study is worth knowing about:

1. It is focusing on a drug that appears to alter abnormal pain processing, which seems to be the primary problem in fibromyalgia.

2. Although this initial study only included 10 women, the idea to explore the use of naltrexone came about when Jarred Younger, PhD, the study's lead author and an instructor in anesthesia and pain management at Stanford, began searching for relief for FM patients. "I was asking patients, 'Does anything work for you?'" he recalled. "A lot of people in support groups were saying, 'Yeah, I tried naltrexone and it works for me.' It just kept coming up." So there was quite a bit of anecdotal evidence even before the study.

3. The results were quite impressive. Pain and fatigue were reduced by an average of 30 percent, some participants decided to come off of other medications, and some were able to go back to work. Overall, there seemed to be significant improvement in their quality of life. Some of the women in the study continued to take the medication after the study ended because their results were so positive.

Even though the results of this study are promising and notable, it's important to remember that it was still just a preliminary study. The researchers remain cautious about recommending the drug this early in the research process. They are, however, moving ahead with a second, longer-term trial of 30 patients who will be tested during a 16-week period. I'm looking forward to hearing the results of that study.